The awk just gives you the second field of each line, which is the PID.

The $(x) construct means to execute x then take its output and put it on the command line. The output of that ps pipeline inside that construct above is the list of process IDs so you end up with a command like kill 1234 1122 7654.

By default Bootstrap does not provide grid system that allows us to create five columns layout, but as you can see it’s quite simple.

At first you need to create default column definition in the way that Bootstrap do it. I called my classes col-..-15.

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.col-xs-15,

.col-sm-15,

.col-md-15,

.col-lg-15 {

position:relative;

min-height:1px;

padding-right:10px;

padding-left:10px;

}

Next you need to define width of new classes in case of different media queries.

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.col-xs-15 {

width:20%;

float:left;

}

@media (min-width: 768px) {

.col-sm-15 {

width:20%;

float:left;

}

}

@media (min-width: 992px) {

.col-md-15 {

width:20%;

float:left;

}

}

@media (min-width: 1200px) {

.col-lg-15 {

width:20%;

float:left;

}

}

Now you are ready to combine your classes with original Bootstrap classes. For example, if you would like to create div element which behave like five columns layout on medium screens and like four columns on smaller ones, you just need to use something like this:

If you do not want to modify the hostname for your instance, but you would like to have a more useful system name (such as webserver) displayed than the private name supplied by AWS (for example, ip-12-34-56-78), you can edit the shell prompt configuration files to display your system nickname instead of the hostname.

Edit the file and change the shell prompt variable (PS1) to display your nickname instead of the hostname. Find the following line that sets the shell prompt in /etc/bashrc (several surrounding lines are shown below for context; look for the line that starts with [ “$PS1”):

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# Turn on checkwinsize

shopt-scheckwinsize

["$PS1"="\\s-\\v\\\$ "]&&PS1="[\u@\h \W]\\$ "

# You might want to have e.g. tty in prompt (e.g. more virtual machines)

# and console windows

And change the \h (the symbol for hostname) in that line to the value of the NICKNAME variable.

On a Linux instance, the public key content is placed in an entry within ~/.ssh/authorized_keys. This is done at boot time and enables you to securely access your instance without passwords. You can open this file in an editor to view the public key for your key pair. The following is an example entry for the key pair named my-key-pair. It consists of the public key followed by the name of the key pair.

You can use ssh-keygen to get the public key for your key pair. Run the following command on a computer to which you’ve downloaded your private key:

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ssh-keygen-y

When prompted to enter the file in which the key is, specify the path to your .pem file; for example:

/path_to_key_pair/my-key-pair.pem

The command returns the public key.

If this command fails, ensure that you’ve changed the permissions on your key pair file so that only you can view it by running the following command: